If the MicroBrute uses the same MIDI implementation as the MiniBrute I am afraid it is going to be difficult as they do not have Modulation Matrix with which you can choose the Source of Modulation (in our case CC#2 Breath Control) to the parameter destination (e.g. In this case VCF Frequency Cut Off) on the MiniBrute the only Modulation Wheel CC#1 and the Aftertouch therefore if you want to use the breath Control you need to remap the CC#2 to CC#1 using an external device such as MIDI Solutions Event Processor Plus or using a software application such as Mainstage 3 (on Mac) Cantabile or BloXpender on PC

you can also remap the breath control to CC#1 or Aftertouch directly from the Sylphyo, so no need to add hardware or software MIDI processor.
Question is more how to map such MIDI CC or Aftertouch to useful parameter like VCA Amp or VCF Cutoff ...

On the MicroBrute, only thing you would be able to control from CC#1 is the Filter Cutoff, but we didn't found any way to get external control to the VCA or to the sustain level of the enveloppe controlling the VCA.
Besides, these parameter are not available from the MOD MATRIX so there is no way for now to have an interesting control of the Microbrute.

you can also remap the breath control to CC#1 or Aftertouch directly from the Sylphyo, so no need to add hardware or software MIDI processor.
Question is more how to map such MIDI CC or Aftertouch to useful parameter like VCA Amp or VCF Cutoff ... so a small modular case would be necessary for such purpose.

The original Minibrute can have these parameters (VCA gain and VCF Cutoff) controlled through CV/Gate so in this case in would be possible but would require a MIDI CV/Gate interface that can translate at least one MIDI CC to 2 CV level ideally each with a level knob.

I do agree with you Laurent regarding the remapping directly from the Sylphyo but this means it will apply for all sounds so you need to have a specific setup for the Mini or MicroBrute and for other synths or VSTi which makes it difficult to use in LIve stituation as you will have to set it up differently each time you change synth unless you have the possibility to save different settings in the Sylphyo you can recall at any time ?
regards
Fred